I think people in general tend to underestimate the Iron Curtain thing, the shift of milieu thing, the shift of big/small ice surface thing, the strength of team thing, the Ed Belfour thing (in this particular case), the team dependence thing, et cetera. Just look at how long it took for Larionov and Fetisov to find their thing in the NHL in Detroit, and that was still a thing designated to play on their strengths after they had already gone through other NHL teams with not as much success (although they had still played respectably well in Vancouver/San Jose & New Jersey).
Dominik Hasek's WC stats in the 80s, before he became an NHL goalie, just b r u t a l i z e s John Vanbiesbrouck's WC stats in the 80s, for instance, when he was a Vezina winning NHL starting goalie.
(games played within parenthesis)
Hasek: 2.50 (2), 2.12 (9), 2.19 (9), 2.10 (10), 2.50 (8)
Vanbiesbrouck: 5.64 (9), 4.01 (7), 4.53 (5), 4.67 (10)
Now, I would say I'm of the opinion myself that I think Hasek was probably generally a better goalie than Vanbiesbrouck in the 1980s, but you probably shouldn't come to that conclusion simply by looking at those numbers posted above, because they seem to indicate that he was twice as good. Firstly, Czechoslovakia was a better team internationally than the Americans, and they played a very sneaky game/system ideally suited for the big ice game, and all those tourneys were played in big ice in Europe. Secondly, if you look at Hasek's and Vanbiesbrouck's Canada Cup stats from the same time sphere
Hasek: 4.00 (4), 3.33 (6), 3.60 (5)
Vanbiesbrouck: 2.00 (4), 3.00 (1)
the tables seems a bit turned, although by not as large gaps (and with a bit smaller sample size).
When Kent Nilsson scored that "Forsberg" goal on Vanbiesbrouck during the 1989 Worlds the Swedish broadcasters didn't even mention Vanbiesbrouck's name, they just called him "the American goalie". If some random/casual Swedish fan looked at that goal, with that stream, and then took a quick look at Vanbiesbrouck's WC stats over the decade, and then was told this Vanbiesbrouck guy was actually a Vezina winning NHL starting goalie with the New York Rangers, they might have come to the (perhaps relatively silly) conclusion that "lol, we'll just send Tommy Söderström over there, he'll contend for the Vezina in any given year, at least he can stop a beach ball if it's multi-colored, hahaha". Because that's how I feel about judging Hasek on 2 games he played against Jimmy Waite in the early stages of his NHL career.
